CN101132172A - Device for preventing a pop noise in an audio output apparatus and method therefor - Google Patents

Device for preventing a pop noise in an audio output apparatus and method therefor Download PDF

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Publication number
CN101132172A
CN101132172A CNA2007101477272A CN200710147727A CN101132172A CN 101132172 A CN101132172 A CN 101132172A CN A2007101477272 A CNA2007101477272 A CN A2007101477272A CN 200710147727 A CN200710147727 A CN 200710147727A CN 101132172 A CN101132172 A CN 101132172A
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CN
China
Prior art keywords
audio codec
audio
electric capacity
codec
control unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CNA2007101477272A
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Chinese (zh)
Inventor
郑秉相
金学洙
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Samsung Electronics Co Ltd
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Samsung Electronics Co Ltd
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Filing date
Publication date
Application filed by Samsung Electronics Co Ltd filed Critical Samsung Electronics Co Ltd
Publication of CN101132172A publication Critical patent/CN101132172A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
    • H03F1/305—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in case of switching on or off of a power supply
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/24—Signal processing not specific to the method of recording or reproducing; Circuits therefor for reducing noise
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G11B20/18—Error detection or correction; Testing, e.g. of drop-outs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/22—Signal processing not specific to the method of recording or reproducing; Circuits therefor for reducing distortions
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/34—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise signals, e.g. squelch systems
    • H03G3/348—Muting in response to a mechanical action or to power supply variations, e.g. during tuning; Click removal circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/03—Indexing scheme relating to amplifiers the amplifier being designed for audio applications
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/345—Pulse density modulation being used in an amplifying circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/351—Pulse width modulation being used in an amplifying circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/417—A switch coupled in the output circuit of an amplifier being controlled by a circuit
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/48—Indexing scheme relating to amplifiers the output of the amplifier being coupled out by a capacitor

Abstract

An audio output apparatus having an audio codec for generating audio signals delivered to a speaker is provided with a device for preventing an audio pop noise caused by the bias voltage output from the audio codec, which includes a capacitor connected between an output end of the audio codec and the speaker, a capacitor charger for smoothly charging the capacitor to a predetermined voltage level, a switch arranged between the junction of the output end of the audio codec and the capacitor and the capacitor charger, and a control unit for controlling the codec, wherein the control unit turns on the switch and drives the capacitor charger before activating the audio codec, and then turns off the switch and terminates the operation of the capacitor charger if a predetermined charging time has elapsed. A method for preventing the audio pop noise caused by a bias voltage output from the audio codec includes smoothly charging the capacitor to have the same voltage level as the bias voltage of the audio codec before activating the audio codec, and activating the audio codec.

Description

In audio output apparatus, avoid plosive devices and methods therefor
Technical field
The present invention relates generally to a kind of audio output apparatus, specifically, relate to a kind of plosive devices and methods therefor of causing at audio output apparatus of being used for avoiding.
Background technology
As shown in Figure 1, audio output apparatus generally includes: control unit 100, audio codec (encoder/decoder) 110, electric capacity 120 and loud speaker 130.Drive audio codecs 110 by control unit 100, being corresponding analoging sound signal with audio data decoding.
When audio codec 110 activates, open the amplifier of the output that is placed in audio codec 110, thereby make the bias voltage of amplifier increase suddenly.The unexpected increase of bias voltage produces and is applied to the alternating current of loud speaker 130 by electric capacity 120, thereby causes plosive.Simultaneously, this bias voltage is stored in the electric capacity 120, thereby, because there is not discharge path, so do not discharge in the operating period of audio codec 110.Yet,, for electric capacity 120 is discharged, form from electric capacity 120 to audio codec 110 discharge path if close audio codec.Therefore, when audio codec 110 was activated, bias voltage was charged again, thereby caused plosive.Recently, cause new problem in the sound source of this plosive in being installed in mobile communication terminal, wherein, described mobile communication terminal is developed to have the multimedia function of enhancing.
Summary of the invention
Therefore, the object of the present invention is to provide a kind of plosive apparatus and method of when activating audio codec, causing avoided.
According to an aspect of the present invention, be provided with the audio output apparatus of the audio codec that is used for producing the audio signal that is sent to loud speaker, be used to avoid the plosive device of audio frequency that causes by bias voltage from audio codec output, comprise: electric capacity is connected between the output and loud speaker of audio codec; Capacitor charger is used for electric capacity is steadily charged to predetermined voltage level; Switch is placed between the joint and capacitor charger of the output of audio codec and electric capacity; And control unit, be used to control codec, wherein, control unit is used for opening switch and drive capacitor charger before activating audio codec, if mistake of predetermined charging interval subsequently, then control unit off switch and stop the operation of capacitor charger.
According to a further aspect in the invention, be provided with the audio output apparatus of the audio codec that is used for producing the audio signal that is sent to loud speaker, be used to avoid the plosive method of audio frequency that causes by bias voltage from audio codec output, comprise: before activating audio codec, electric capacity steadily charged to have the voltage level identical, and activate audio codec with the bias voltage of audio codec.
Description of drawings
Following detailed description in conjunction with the drawings, above-mentioned and other purposes of the present invention, characteristics and advantage will become apparent, wherein:
Fig. 1 is the block diagram that the circuit of conventional audio output equipment is shown;
Fig. 2 illustrates the block diagram that is used to avoid the circuit of plosive audio output apparatus according to of the present invention;
Fig. 3 A and Fig. 3 B illustrate the curve chart that changes with the pulse duration of pulse width modulation (PWM) pulse signal according to charging interval of electric capacity of the present invention;
Fig. 4 A and Fig. 4 B illustrate the curve chart that changes with the impulse density of pulse density modulated (PDM) pulse signal according to charging interval of electric capacity of the present invention; And
Fig. 5 illustrates the flow chart of avoiding the processing of plosive audio output apparatus according to of the present invention.
Embodiment
Below, the preferred embodiments of the present invention are described with reference to the accompanying drawings.In the accompanying drawings, although same or analogous parts are represented them shown in the different accompanying drawings by same-sign.In the following description, because known function or structure will be blured the present invention in unnecessary details, therefore omit description of them.
The invention provides a kind of have be used to produce the audio output apparatus of audio codec that is sent to the audio signal of loud speaker by electric capacity, this equipment is before activating audio codec, electric capacity steadily charged to have the voltage level identical with the bias voltage of audio codec, thereby the voltage difference between the bias voltage of the audio codec of eliminating electric capacity substantially and when activating audio codec, taking place, thereby avoid the audio frequency plosive.
With reference to Fig. 2, be used for avoiding plosive contrive equipment to comprise: capacitor charger 200, control unit 201, audio codec 210, electric capacity 220, loud speaker 230 and switch 240 at audio output apparatus.Drive capacitor charger 200 to charge by control unit 201 by 240 pairs of electric capacity 220 of switch.Capacitor charger 200 comprises pulse generator 202 and integrating circuit 203.
Pulse generator 202 produces predetermined pulse signal under the control of control unit 201.Pulse generator 202 produces pulse signal, and described pulse signal can be in pulse density modulated (PDM) pulse signal and pulse width modulation (PWM) pulse signal.203 pairs of pulse signals that produce from pulse generator 202 of integrating circuit carry out integration, are used for the electric capacity charging voltage that electric capacity 220 is charged with generation.Control unit 201 drove capacitor charger 200 and opens switch 240 before activating audio codec 210, with all functions of control audio output equipment, thereby avoid plosive.
Audio codec 210 is converted to corresponding simulated audio signal with digital audio-frequency data, adjusts the also size of amplified analog audio signal simultaneously.Be sent to loud speaker 230 from the audio signal of audio codec 210 outputs.
Switch 240 is connected between the joint and integrating circuit 203 of the output of audio codec 210 and electric capacity 220, thereby it is open at the charge path between integrating circuit 203 and the electric capacity 220, and discharges to integrating circuit 203 with the electric capacity of avoiding charging 220 in the charge closing path.
Yet, it should be noted that, activate before the audio codec 210 with electric capacity 220 quick charges to the bias voltage of audio codec 210 be equal to level the time, the identical plosive that the bias voltage of audio codec 210 causes can take place.In order to eliminate this problem, be necessary to determine with the steady charging interval of charging and being spent of electric capacity.Can determine this charging interval by emulation at the during the design of invention audio output apparatus.This charging interval also can be with changing for the pulse signal of being scheduled to that electric capacity 220 is steadily charged.
What describe below in conjunction with Fig. 3 A and Fig. 3 B is to change with the pulse duration of pulse width modulation (PWM) signal in charging interval of electric capacity 220.In this case, Fig. 3 A illustrates the pulse duration of the pwm signal of setting 20%, and Fig. 3 B illustrates the pulse duration of the pwm pulse signal of setting 50%.
With reference to Fig. 3 A, if pulse generator 202 produces and is applied to having of integrating circuit 203 and is set at 20% pwm pulse, then being used for electric capacity 220 is charged to the time that bias level spends is t a, shown in the curve chart of bottom.Yet, with reference to Fig. 3 B, if pulse duration is set at 50%, with the situation that is set at 20% pulse duration charging interval t relatively aBecome shorter.Therefore, be used for the time t that charging is spent to electric capacity aPulse width variation with predetermined pwm pulse.Therefore, when having predetermined pwm pulse signal, wish pulse duration suitably is adjusted at and be used to avoid in the plosive scope that the unexpected charging by electric capacity 220 causes.Be appreciated that described predetermined pulse signal also can be used for predetermined charging interval t a
Selectively, pulse signal producer 202 can be designed to produce PDM pulse signal rather than pwm pulse signal, shown in Fig. 4 A and Fig. 4 B.What describe below in conjunction with Fig. 4 A and Fig. 4 B is to change with impulse density in charging interval of electric capacity 220, and wherein, Fig. 4 A illustrates the situation of low impulse density, and Fig. 4 B illustrates the situation of high pulse densities.As shown in the figure, be used for electric capacity 220 is charged to the time t that bias level spends aChange with impulse density.Therefore, as the situation of pwm pulse, when having predetermined PDM pulse signal, also wish impulse density suitably is adjusted at and be used to avoid in the plosive scope that the unexpected charging by electric capacity 220 causes.Be appreciated that the charging interval of considering being used to avoid in the plosive scope, can change the pulse duration of pwm signal and the impulse density of PDM signal arbitrarily.
Fig. 5 illustrates the flow chart that control is used to avoid the processing of plosive audio output apparatus, wherein, suppose pulse generator 202 generation pwm pulse signals.In step 500, control unit 201 was opened switch 240 before activating audio codec 210, carry out step 510 subsequently and come sensitizing pulse generator 202.
Pulse generator 202 is activated in step 510, and its produces the predetermined pwm pulse signal that is applied to integrating circuit 203, and described integrating circuit 203 pulse signals integration successively is sent to the charging voltage of electric capacity 220 with generation.Subsequently, whether control unit 201 carries out step 520 and determines mistake of predetermined charging interval.At this, the described predetermined charging interval is the time that bias level spent that is used for electric capacity 220 is charged to audio codec 210.In conjunction with Fig. 3 A and 3B scheduled time t is described more particularly aChange with predetermined pwm pulse signal.
If the scheduled time did not also have, control unit 201 repeating steps 520 then.When scheduled time mistake, control unit carries out step 530 and comes off switch 240 subsequently.When switch 240 is closed, the charge path between integrating circuit 203 and electric capacity 220 is cut off, to avoid electric capacity 220 to integrating circuit 203 discharges.Control unit 201 carries out step 540 and closes pulse generator 202 subsequently, and activates audio codec 210 to step 550 subsequently.
As mentioned above, contrive equipment is avoided changing the plosive that causes by unexpected direct current (DC) when activating audio codec by the bias level that electric capacity 220 is steadily charged to audio codec 210 before the activation audio codec.That is, the electric capacity of pre-charge avoids the unexpected DC of bias voltage to change, and therefore avoids plosive.
In the present invention, the pulse generator generation has the pulse signal of identical value up to being closed, and still as long as the unexpected rising of recharge voltage level does not cause plosive, then pulse signal can be changed into arbitrarily and have different values.
Although illustrate and described the present invention with reference to some preferred embodiment of the present invention, but it should be appreciated by those skilled in the art that: do not breaking away under the situation of the spirit and scope of the present invention as described in claims, can carry out various changes on form and the details it.

Claims (5)

1. audio output apparatus that is provided with the audio codec that is used for producing the audio signal that is sent to loud speaker is used to avoid the plosive device of audio frequency that caused by the bias voltage from audio codec output, comprising:
Electric capacity is connected between the output and loud speaker of audio codec;
Capacitor charger steadily charges to predetermined voltage level with electric capacity;
Switch is placed between the joint and capacitor charger of the output of audio codec and electric capacity; And
Control unit is controlled described codec, and wherein, control unit was opened switch and also driven capacitor charger before activating audio codec, if mistake of predetermined charging interval subsequently, then control unit off switch and stop the operation of capacitor charger.
2. device as claimed in claim 1, wherein, the predetermined charging interval is the time of level that is used for electric capacity is charged to the bias voltage of described audio codec.
3. device as claimed in claim 2, wherein, capacitor charger comprises:
Pulse generator is driven by control unit, is used to produce the pwm pulse signal that has according to predetermined pulse duration of predetermined charging interval; And
Integrating circuit is connected between pulse generator and the switch, is used for pwm pulse signal is carried out integration, thereby with described electric capacity charging.
4. device as claimed in claim 2, wherein, capacitor charger comprises:
Pulse generator is driven by control unit, is used to produce the PDM pulse signal that has according to predetermined impulse density of predetermined charging interval; And
Integrating circuit is connected between pulse generator and the described switch, is used for the PDM pulse signal is carried out integration, thereby with described electric capacity charging.
5. one kind is provided with and is used for producing the audio output apparatus of audio codec that is sent to the audio signal of loud speaker by electric capacity, is used to avoid the plosive method of audio frequency that caused by the bias voltage from audio codec output, comprises step:
Before activating audio codec, electric capacity is steadily charged, make it have the voltage level identical with the bias voltage of audio codec; And
Activate audio codec.
CNA2007101477272A 2006-08-25 2007-08-27 Device for preventing a pop noise in an audio output apparatus and method therefor Pending CN101132172A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020060081353 2006-08-25
KR1020060081353A KR100810853B1 (en) 2006-08-25 2006-08-25 Apparatus and method for preventing pop noise in audio output apparatus

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Publication Number Publication Date
CN101132172A true CN101132172A (en) 2008-02-27

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US (1) US20080049952A1 (en)
EP (1) EP1892828B1 (en)
KR (1) KR100810853B1 (en)
CN (1) CN101132172A (en)
DE (1) DE602007003058D1 (en)

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CN106972843A (en) * 2017-03-28 2017-07-21 浙江大学 Possess the electronic instrument control signal output circuit and implementation method of defencive function
CN110267142A (en) * 2019-06-25 2019-09-20 维沃移动通信有限公司 A kind of mobile terminal and control method

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CN102638229B (en) * 2012-04-18 2014-12-10 上海艾为电子技术有限公司 Audio amplification circuit
CN106972843A (en) * 2017-03-28 2017-07-21 浙江大学 Possess the electronic instrument control signal output circuit and implementation method of defencive function
CN106972843B (en) * 2017-03-28 2019-10-01 浙江大学 The electronic instrument control signal output circuit and implementation method for having defencive function
CN110267142A (en) * 2019-06-25 2019-09-20 维沃移动通信有限公司 A kind of mobile terminal and control method
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Publication number Publication date
EP1892828A1 (en) 2008-02-27
US20080049952A1 (en) 2008-02-28
KR100810853B1 (en) 2008-03-06
KR20080018754A (en) 2008-02-28
DE602007003058D1 (en) 2009-12-17
EP1892828B1 (en) 2009-11-04

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Open date: 20080227